Manufacturing method of printing circuit board with micro-radiators

ABSTRACT

The present invention relates to a manufacturing method of a printing circuit board. The manufacturing method mainly includes: forming one or more cylindrical micro-radiators by cutting a high conductive and electrical insulating substrate according to predetermined size; manufacturing one or more mounting holes in copper clad plates and prepregs; embedding the cylindrical micro-radiators into the mounting holes. The present invention combines the micro-radiator with high thermal conductivity and traditional stiffness printing circuit board. The printing circuit board with micro-radiators has the advantages of high thermal conductivity and stable heat transfer, and also has the advantages of routing flexibility and reliable electrical connections.

FIELD OF THE INVENTION

The present invention relates to printing circuit boards, particularly,the present invention relates to a manufacturing method of a printingcircuit board with micro-radiators.

BACKGROUND OF THE INVENTION

Printing circuit boards (PCBs) are one of important elements inelectronics industry. PCBs are used as mechanical support elements forthe electronic components, and realize electrical connection among theelectronic components. In addition, graphics and numbers of thecomponents can be printed on the PCBs, it is convenient for furnishing,checking or maintaining the components. The PCBs are used in almostevery electronic device, such as electronic watch, calculator, computer,communication electronics device, military weapon systems.

Traditional PCBs are plated through hole structure, insulation materialamong layers is FR4 material, the thermal conductivity of the insulationmaterial is 0.4 W/mk. In recent years, the thermal conductivity of theinsulation material is 1.3-2.2 W/mk. When plenty of integrated circuits(especially high power LED) are installed on the printing circuit board,the thermal conductivity of the printing circuit board come up to tensor hundreds of W/mk. Obviously, it is far beyond the thermalconductivity of the insulation material of the prior art.

Therefore, there are some shortcomings in the prior art.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a manufacturing methodof the printing circuit board with micro-radiators.

The object of the present invention is realized by use the technicalsolutions as follows:

A manufacturing method of a printing circuit board with micro-radiatorsincludes:

providing a board comprising a thermal conductive and electricalinsulating base and copper foils over an upper surface and a lowersurface of the board, and forming one or more cylindricalmicro-radiators by cutting the board according to predetermined size;

providing single-sided or double-sided copper clad plates and prepregs,forming joined boards by cutting the copper clad plates and prepregsaccording to predetermined size, and manufacturing inner circuit in thecopper clad plates;

manufacturing one or more mounting holes in copper clad plates andprepregs, the shape and size of the mounting holes adapting to thecylindrical micro-radiators;

laminating the copper clad plates and the prepregs, a top layer and abottom layer being copper clad plates, embedding the cylindricalmicro-radiators into the mounting holes;

pressing the copper clad plates and the prepregs;

laminate drilling and electroplating, etching, solder masking andtinning, then being silkscreened and mounting heating elements on anupper surface of micro-radiators.

Compared with the prior art, the present invention combines themicro-radiators with high thermal conductivity and traditional rigidprinting circuit board. The printing circuit board with micro-radiatorshas the advantages of high thermal conductivity and stable heattransfer, and also has the advantages of routing flexibility andreliable electrical connections. The heat coming from the heatingelements can be conducted out of the printing circuit board in time andeffectively. The printing circuit board with micro-radiators is theideal carrier board for the heating element and heating element array.The manufacturing method of the printing circuit board withmicro-radiators has the advantages of simplicity and strongpracticability.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating the printingcircuit board with micro-radiators of the present invention.

FIG. 2 is a flowchart of the manufacturing method of the printingcircuit board with micro-radiators of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, the printing circuit board is a rigid PCB, andincludes a substrate. The substrate consists of 3 layers of copper cladplates 110 and 2 layers of prepregs 120. The 3 layers of copper cladplates 110 and the 2 layers of prepregs 120 are cross-laminated. A toplayer and a bottom layer are copper clad plates 110. An upper surfaceand a lower surface of each copper clad plate 110 are covered coppercircuit 130. The printing circuit board also includes a plurality ofcylindrical micro-radiators 150, each cylindrical micro-radiator 150 isembedded into a cylindrical hole of the substrate. The height of themicro-radiator 150 is equal to the thickness of the substrate. An uppersurface 151 and a lower surface 152 of the micro-radiator are covered bycopper foils. A LED chip 160 is installed on the upper surface 151, andthe power signal input of the LED chip 160 is electrically connected tothe inner circuit of the printing circuit board, and the lower surface152 of the micro-radiator 150 is insulated from other circuits of theprinting circuit board.

A base of micro-radiator 150 is made from electrical insulatingmaterial, such as alumina ceramic, aluminum nitride ceramic, siliconcarbide, diamond, and so on. The thermal conductivity between the uppersurface 151 and the lower surface 152 of the micro-radiator 150 can beachieved to 20-1000 W/mk.

When the LED chip 160 is operating, the LED is lighting and emittingheat continuously. The heat is transferred from the upper surface 151 tothe lower surface 152 of the micro-radiator 150 by the thermalconductive base, then transferred out of the printing circuit board bycopper foil of the lower surface 152.

As shown in FIG. 2, the manufacturing method of the printing circuitboard of FIG. 1 includes the following steps:

A210: providing a board with a high conductive and electrical insulatingbase, and forming a plurality of cylindrical micro-radiators by cuttingthe board according to predetermined size.

The upper surface and the lower surface of the base are covered bycopper foils. The upper surface 151 and the lower surface 152 of eachcylindrical micro-radiator are covered by copper foils.

The base is made from electrical insulating material, such as aluminaceramic, aluminum nitride ceramic, silicon carbide, diamond, and so on.

A220: providing 3 layers of copper clad plates and 2 layers of prepregs,forming joined boards, and manufacturing inner circuit in the copperclad plates.

Forming joined boards of PCB is by cutting the 3 layers of copper cladplates 110 and 2 layers of prepregs according to predetermined size.Manufacturing inner circuit is by using traditional pattern transfermethod.

A230: manufacturing a plurality of mounting holes in copper clad platesand prepregs.

Manufacturing a plurality of mounting holes can be using probing,milling, punching, and so on. The shape and size of the mounting holeadapts to cylindrical micro-radiator 150.

A240: laminating the copper clad plates and the prepregs, and the toplayer and the bottom layer being copper clad plates, and embedding thecylindrical micro-radiators into the mounting holes.

Laminating the copper clad plates 110 and the prepregs is by usingtraditional laminating method of multi-layer PCBs.

A250: pressing the copper clad plates and the prepregs.

Pressing the copper clad plates 110 and the prepregs is by usingtraditional pressing method of multi-layer PCBs.

A260: laminate drilling and electroplating, etching, solder masking andtinning, then being silkscreened and mounting heating elements 160 on anupper surface 151 of micro-radiators 150.

Copper foil over an upper surface of the base is electrically connectedto the inner circuit, and copper foil over a lower surface of the baseis electrically insulated from the inner circuit.

The manufacturing method of the present invention is not limited by thepreferred embodiments, all the equivalent change and modificationaccording to the present invention are covered by the protection scopeof the claims. For example:

In step A260, one or more heating element such as LED elements orintegrated circuit chip can be installed on the upper surface 151 of themicro-radiators 150.

In step A220, the number of the copper clad plates 110 can be N(N>1),the number of the prepregs can be N−1, and the number of the layers ofthe printing circuit board is 2N−1.

In step A220, the single-sided or double-sided copper clad plates areprovided. If the single-sided copper clad plates are provided, both atop surface and a bottom surface of the multi-layer printing circuitboard should be copper clad during the process of pressing the copperclad plates and the prepregs.

In step A210, the micro-radiator is elliptic cylindrical, cube-shaped orcylinder shape, when the micro-radiator is cylinder shape, both theupper surface and the lower surface are rhombus, triangle or trapezoid.The number of the micro-radiators depends on the need of the actualcircuit, it can be one or more.

Heating elements are electrically connected to the inner or outercircuit of the printing circuit board.

1. A manufacturing method of a printing circuit board withmicro-radiators, including: providing a board comprising a thermalconductive and electrical insulating base and copper foils over an uppersurface and a lower surface of the board, and forming one or morecylindrical micro-radiators by cutting the board according topredetermined size; providing single-sided or double-sided copper cladplates and prepregs forming joined boards by cutting the copper cladplates and prepregs according to predetermined size, and manufacturinginner circuit in the copper clad plates; manufacturing one or moremounting holes in copper clad plates and prepregs, the shape and size ofthe mounting holes adapting to the cylindrical micro-radiators;laminating the copper clad plates and the prepregs, a top layer and abottom layer being copper clad plates, embedding the cylindricalmicro-radiators into the mounting holes; pressing the copper clad platesand the prepregs; laminate drilling and electroplating, etching, soldermasking and tinning, then being silkscreened and mounting heatingelements on an upper surface of micro-radiators.
 2. The manufacturingmethod of the printing circuit board of claim 1, wherein, themicro-radiator is elliptic cylindrical, cube-shaped or cylinder shape,when the micro-radiator is cylinder shape, both the upper surface andthe lower surface are rhombus, triangle or trapezoid.
 3. Themanufacturing method of the printing circuit board of claim 1, wherein,the thermal conductive and electrical insulating base is made fromalumina ceramic, aluminum nitride ceramic, silicon carbide, or diamond.4. The manufacturing method of the printing circuit board of claim 1,wherein the copper foil over an upper surface of the micro-radiator iselectrically connected to the inner or outer circuit, and the copperfoil over a lower surface of the micro-radiator is electricallyinsulated from the inner and outer circuit.
 5. The manufacturing methodof the printing circuit board of claim 1, wherein both a top surface anda bottom surface of the multi-layer printing circuit board are copperclad.
 6. The manufacturing method of the printing circuit board of claim1, wherein the heating elements are LED chips.
 7. The manufacturingmethod of the printing circuit hoard of claim 1, wherein manufacturingone or more mounting holes can be using probing, milling, or punching.8. The manufacturing method of the printing circuit board of claim 1,wherein the number of the copper clad plates can be N, the number of theprepregs can be N−1, and the number of the layers of the printingcircuit board is 2N−1.